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【单选题】
某组分在薄层色谱中展开,5min时测得比移值为Rf,10min时的展开结果是( )A.
Rf加倍
B.
组分移行距离增加,但小于2倍
C.
Rf减小
D.
组分移行距离增加,但大于2倍
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反馈参考答案：
举一反三
【单选题】Which of the following sentence adopts a diffferent rhetorical device from the rest three?
A.
The world is watching closely what the White House will do next.
B.
I, too, felt the compulsive hand of nature and began to find that pointing out contradictions could be costly as well as fun.
C.
Democracy favors the vote rather than the bullet.
D.
It never occurred to him that the pen could be mightier than the sword.
【单选题】对于循环语句下列描述正确的是（ ）
A.
while和do-while实现的效果一样
B.
while循环可以用for循环代替
C.
while(1)表示无限循环
D.
continue可以跳出循环
【单选题】Which of the following sentence has the opposite meaning from the other three?
A.
You are telling me.
B.
You may well say so.
C.
You can say that again.
D.
That's not saying very much.
【单选题】Which of the following sentence has the different meaning from the other three?
A.
You are telling me.
B.
You may well say so.
C.
You can say that again.
D.
That's not saying very much.
【简答题】化合酸( C.A. )
【单选题】关于while和for的区别，下列叙述中正确的是
A.
while语句的循环体至少无条件执行一次，for语句的循环体可能一次都不执行
B.
while语句只能用于循环次数未知的循环，for语句只能用于循环次数已知的循环
C.
在很多时候，while和for可以等价使用
D.
while语句只能用于可迭代变量，for语句可以用任意表达式表示条件
【单选题】Listen to the rhythm of the following sentences. Which sentence does not have three stressed syllables?
A.
She's gone for a walk in the park.
B.
The others must have been waiting for a while.
C.
She ought to know the way by now.
D.
We've been waiting for an hour and a half.
【多选题】以下关于总效用和边际效用说法正确的是
A.
总效用是消费者在消费商品时所感受的总满足程度
B.
边际效用是消费者增加一单位某种商品的消费所增加的满足程度
C.
边际效用递减时，总效用递减
D.
边际效用大于零时，总效用递增
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